Electromagnetic device



June 20, 1961 w. PARISOE 2,989,668

I ELECTROMAGNETIC DEVICE Filed May 29. 1959 2 Sheets-Sheet 1 IN VEN TOR.

June 1961 w. PARISOE I 2,989,668

' ELECTROMAGNETIC DEVICE Filed May 29, 1959 2 Sheets-Sheet 2 UnitedStates Patent 2,989,668 ELECTROMAGNETIC DEVICE Wilbert Parisoe, HighlandPark, Ill., assignor to Oak Manufacturing Co., a corporation of DelawareFiled May 29, 1959, Ser. No. 816,818 6 Claims. (Cl. 317-176) Thisinvention relates to an electromagnetic device having a movable armatureoperated by a winding and particularly to a solenoid for controlling theduration of an operating cycle.

The solenoid to which this invention is applicable is more fullydisclosed in United States Patent No. 2,430,949, issued November 18,1947 to Leland. Such a solenoid is useful for operating rotary switchesand an application of this solenoid to rotary switches is disclosed inUnited States Patent No. 2,812,453, issued on November 5, 1957 toMastney.

In this last-named patent, means are provided for preventing overshootof the load due to the fact that the solenoid armature is operating atmaximum speed near the end of its stroke. As is more fully disclosed inthe first-mentioned patent to Leland, the solenoid has an armature whichis adapted to turn inwardly toward the solenoid structure duringenergization.

The operating winding is a simple coil having a suitable ferro-magneticstructure including as a part thereof a movable armature. In thespecific embodiment of the invention, the armature is rotatable througha predetermined fixed angle and is also translatable along its axisduring rotation. The means for controlling the armature movement isfully disclosed in the prior patents and will also be described herein.

In connection with the operation of such a solenoid, it has been foundthat the speed of movement of the armature during energization of thewinding is influenced by the potential applied to the winding forenergizing the same. Inasmuch as the solenoid is generally provided withautomatic switching means for opening the energizing circuit after thearmature has moved through its pre scribed range, and since the armatureis restored to its initial starting position automatically by suitablemeans, it has been found that the overall operating time of a solenoidis subject to wide fluctuations depending upon the magnitude of theapplied potential.

Such solenoids are energized by direct current and in certainapplications it is important that the duration of an entire operatingcycle for the solenoid be substantially constant in spite of variationsin applied potential. Inasmuch as the time taken by the armature inmoving during energization of the windings is cut down substantiallywith increase in potential, it follows therefore that it is necessary todelay the return stroke of the armature to maintain the overall periodgenerally constant.

The mechanism with which the rotary solenoid is generally associated,examples of which are disclosed in the patents previously identified,makes it impractical to control the speed of return of the armature byoperating on such mechanism. This invention provides simple means forcontrolling the speed of return stroke of the armature of a solenoid. Inthe specific example disclosed, the duration of the armature return isautomatically increased as the speed of armature movement duringenergization increases in response to increased applied potential. Inshort the invention makes possible a controlled delay action on armaturemovement.

The invention generally contemplates the provision of a short circuitedwinding closely coupled to the energizing winding of the solenoid, theshorted winding being disposed in a portion of the solenoid so that thestroke of the armature is affected. In order to provide an adjustablecontrol over the return stroke, one form of the inice ventioncontemplates the provision of a resistor disposed across the operatingwinding during the return stroke. By controlling the value of theresistor, the return characteristics of the armature may be accuratelycontrolled. In another form of the invention, means are provided fordirectly varying the ohmic resistance of a shorting ring.

It has been found that the overall duration of an operating cycle for asolenoid embodying the improvements suggested above is maintained withinclose limits over substantial variations of operating potential for thesolenoid. It is understood that any time during which the armature ismaintained in energized position is not included in operating time. Itis clear that an armature may be retained in energized positionindefinitely providing the energizing winding does not overheat. It hasalso been found that a flexible simple control for the speed ofoperation of an armature for any type of electromagnetic device can beprovided by means of the present invention.

In order that the invention may be fully understood, it will now bedisclosed in detail in connection with the drawings wherein FIGURE 1 isa sectional view taken on the line 1-1 of FIGURE 2 showing the newsolenoid.

FIGURE 2 is a section through a portion of the solenoid to illustratethe windings and certain of the mechanical structure, this figure alsoshowing in diagrammatic form the circuit connections for the winding.

FIGURE 3 isa bottom view of the device illustrated in FIGURE 2.

FIGURE 4 is a top view of the solenoid embodying the present invention,this view showing in diagrammatic form the switch for opening theenergizing circuit at the end of an operating stroke.

FIGURE 5 is a bottom view.

FIGURE 6 is an exploded view of a modification.

FIGURE 7 is a sectional elevation along lines 7-7 of FIGURE 5 showingthe modification.

FIGURE 8 is a detail of the short circuiting ring of the modification.

Referring first to FIGURES l to 3 inclusive, the solenoid to which thisinvention may be applied has ferromagnetic housing 10 having top edge 11and inwardly directed flange portion 12 at the bottom thereof. Flangeportion 12 terminates in annular cylindrical surface 13. Cooperatingwith housing 10 is annular member 15 which in section is generallyangle-shaped. Housing 10 and annular member 15 cooperate to provide agenerally toroidal region 16 within which is disposed winding 17 forenergizing the solenoid. It is understood that housing 10 .and member 15are both of suitable ferro-magnetic material, such as soft iron, andthat members 10 and 15 are fitted together snugly to reduce reluctance.

Annular member 15 has bore 18 which is generally coaxial with toroidalregion 16. Within bore 18 is nonmagnetic stub shaft 20 which is movableboth longitudinally and rotationally. Rigidly secured to stub shaft 20is armature 21. Armature 21 has generally cylindrical surface 22 spacedfrom cylindrical surface 13 by a small clearance to permit armaturemovement. Armature 21 has end face 23 which is spaced from end face 24of annular member 15 by an air gap whose magnitude will vary witharmature movement.

In order to control the movement of the armature and force the same tohave a corkscrew motion, metal plate 26 is rigidly attached thereto. Itis preferred to have metal plate 26 of ferro-magnetic material in orderto improve the eificiency of operation. As will be apparent later, itmakes no difference whether metal plate 26 is directly attached toarmature 21 or to stub shaft 20.

As is more fully disclosed in the Leland patent referred to. theopposing surfaces of plates 26 and housing portion 12 are provided witha plurality of arcuate cam grooves a 27 and 28, respectively, withinwhich balls 29 may ride. A steel ball 29 is provided for eachcooperating pair of cam grooves 27 and 28. The cam grooves are arcuatewith respect to the axis of shaft 20 and the arc angle will depend uponthe desired solenoid stroke.

The depth of cam grooves 27 and 28 varies so that as ball 29 moves alongthe two cam grooves, due to relative rotation of the armature andhousing, the cam action will permit plate 26 to approach part 12 of thehousing during energization. Upon de-energization of the winding,suitable means, such as spring 30, will rotate the armature in thereverse direction causing the plate 26 to move away from the flange partof the housing.

Insofar as the present invention is concerned, the structure so fardescribed may be considered as conventional and other means for securingtravel of an armature may be provided.

In accordance with the present invention, copper ring 31 is disposedwithin toroidal region 16 adjacent edge portion 11 of the housing. Thiscopper ring has one turn or may be replaced by a winding whose ends areconnected together to short circuit the same. The ring or winding, asthe case may be, will be designed so that the movement of the armatureon the return stroke will be delayed a desired amount. This will becontrolled by the ring dimensions or coil turns. As is well understood,the close coupling between the ring and ferromagnetic circuit causes thering to act as a shorted transformer winding.

Due to manufacturing tolerances, it is preferred to provide a Vernieraction in the form of a variable resistor and a rectifier although thelatter may be omitted if desired. The variable resistor and rectifiermay be connected in series with what may be termed the short-circuitedsecondary designated here as 31. However, if a short circuited ring isused, it is preferred to have the resistor and rectifier acrossoperating Winding 17. Accordingly, resistor 33 and rectifier 34 areconnected across winding 17.

As has been indicated above, rectifier 34 may be omitted but if insertedthe rectifier should be so poled as to permit passage of current throughthe resistor from the operating winding during the return stroke of thearmature. This current will flow in opposite direction to the flow ofcurrent when the solenoid is energized from. a suitable d.e. potentialsource. The resistor may be permanently connected across the operatingwinding or may be switched across the winding only during the returnstroke by automatic switching means. Where automatic switching means areused, it will be unnecessary to provide a rectifier since the resistorwill not be connected across the operating winding during energization.

The application of an abnormally high direct voltage to the operatingwinding will magnetize the ferromagnetic structure more intensely andresult in a much faster movement of the armature. Due to the greaterflux density in the iron resulting from the higher energizing current,the decay of the current in the operating winding which occurs aftercurrent is shut off may be delayed thus reducing the speed of returnmovement of the armature in response to its spring bias. It has beenfound that the total operating time of a solenoid can be constant withinclose limits in spite of substantial varia tions of operating time ofthe armature during energization as a result of differences inenergizing potential.

Referring now to FIGURES 4 to 8 inclusive, a modification of theconstruction embodying the present invention is shown. As has beenpreviously indicated, the short circuiting ring in the constructionillustrated in FIGURES 1 to 3 inclusive may be considered as atransformer secondary which is closely coupled to the operating windingfunctioning as a transformer primary. In the form of the inventionillustrated in FIGURES 1 to 3 inclusive, the loss due to the resistoracross the energizing winding (the primary of the transformer during thereturn stroke) is reflected in the secondary and results in a delayaction. In the modification now to be described, the construction hasbeen modified so that the resistance is physically in the shortcircuiting ring.

The modified construction illustrated in FIGURES 4 to 8 inclusive isgenerally similar to that illustrated in FIGURES 1 to 3 inclusiveinsofar as the rotary mechanism, energizing winding and other mechanicaldetails.

As illustrated in FIGURE 4-and this applies equally well to themodification illustrated in FIGURES l to 3 inclusive-a switch comprisingmovable contact 40 cooperating with fixed contact 41 is provided. Thisswitch is normally closed in the idle position of the armature. However,when the solenoid has been energized and the armature has been turned,plate 42, secured to the armature, is adapted to open the switch nearthe end of the armature stroke. The means for accomplishing this mayconsist of a suitably shaped portion of the contact arm operated byplate 42.

In the modified construction, there is ring 31' which differs from ring31. Ring 31' is split at 44 to open the ring. The split is here shown ascomplete to provide an electrical discontinuity in the ring. However, ifdesired, the split may extend from the outside of the ring inwardly partway. Ring 31 has a tapped recess provided at the split to accommodatescrew 45. Ring 31 is preferably of copper or other low resistancematerial and screw 45 is also of copper or other low resistancematerial. The ring is so machined and cut that screw 45 will engage thethreads very tightly to make good electrical contact. By controlling thedepth of penetration of screw 45 into the ring, the electricalresistance of the ring as a short circuiting member can be accuratelycontrolled. If desired, screw 45 may be of higher resistance material,such as brass, or the ring may be of brass and the screw may be ofcopper.

In order to permit screw 45 to be adjusted externally, the housing maybe provided with an aperture through which the screw may project or intowhich a screw driver may be inserted for reaching the head of screw 45.

Instead of having a simple machine screw as illustrated, it is possibleto have a tapered pin operate in a tapered slot in the ring. Thus, atapered pin will have'a sort of cam effect and will open the ring as thepin goes in to bridge an increasing amount of metal. I

In the modification illustrated here, it is desirable to provideelectrical insulation 47 around the short circuiting ring, or at leastaround the part where split 44 occurs. This is to prevent the metal ofthe housing from short circuiting the split in the ring.

While the invention has been illustrated in connection with a rotarysolenoid, it is understood that it may be applied to otherelectromagnetic devices where a short circuiting winding is used. Thus,there are many instances where a copper Slug or ring is used to providea delay action. By opening the ring and providing an adjustable metalinsert for controlling the electrical resistance of the short circuitingring, the effects of the ring may be accurately controlled.

This is a continuation-in-part of my application, Serial No. 777,304,filed December 1, 1958, and now abandoned.

What is claimed is:

1. An electromagnetic device having an operating winding andferro-magnetic core structure, including an armature movable in responseto magnetic flux in said core and armature, said operating winding beingadapted to be energized by direct current for obtaining armaturemovement, a split short circuiting copper ring closely coupled to saidwinding, said split ring comprising a normally open single turn windingwhich is adapted to function as a secondary of a transformer whoseprimary is the operating winding, a copper member shaped to fit into thesplit of the ring and means for controlling the insertion of the memberinto the split portion to provided copper controi the amount of copperbridging the split whereby the ohmic resistance of the split ring can beaccurately controlled and thereby control the delay characteristics ofthe device.

2. The construction according to claim 1 wherein said means forcontrolling the insertion of the member comprises cooperating threadsupon the member and in the split portion of the ring, said copper memberconstituting a copper bolt which can be threaded into the split to anydesired depth.

3. A rotary solenoid having a substantially constant operating periodover wide variations of energizing current, said solenoid comprising agenerally toroidal ferromagnetic structure, said ferro-magneticstructure having a shaft disposed at the axis of the toroid and havingattached thereto as an armature a portion of the ferromagneticstructure, said armature being movable around and along the toroid axis,means for limiting the movement of said armature and shaft to a partialturn with longitudinal travel of the armature along toroid axis toimpart a corkscrew movement thereto, said armature being separated fromthe remainder of the ferro-magnetic structure by an air gap whosemagnitude is increased to a maximum value when said armature is at oneend of its travel, means for biasing said armature to said one end ofits travel from which upon solenoid energization said armature movestoward the other end of its travel range, an energizing winding withinan annular chamber of the toroidal ferromagnetic structure,

a split copper ring within said toroidal chamber, a copper member shapedto fit into the split portion of the ring and means for controlling theinsertion of the copper member into the split portion of the ring tocontrol the amount of copper bridging the split whereby the ohmicresistance of the split ring can be accurately controlled and therebycontrol the delay characteristics of the solenoid.

4. The construction according to claim 3 wherein said means forcontrolling the insertion of the member comprises cooperating threadsupon the member and in the split portion of the ring, said copper memberconstituting a copper bolt which can be threaded into the split to anydesired depth.

5. The construction according to claim 4 wherein said copper ring islocated in said toroidal region remote from said movable armature.

6. The construction according to claim 5 wherein said toroidalterm-magnetic structure is apertured of provide access to said copperbolt from the exterior of said solenoid.

References Cited in the file of this patent UNITED STATES PATENTS

